// 
// Copyright(c) 2009 Syntext, Inc. All Rights Reserved.
// Contact: info@syntext.com, http://www.syntext.com
// 
// This file is part of Syntext Serna XML Editor.
// 
// COMMERCIAL USAGE
// Licensees holding valid Syntext Serna commercial licenses may use this file
// in accordance with the Syntext Serna Commercial License Agreement provided
// with the software, or, alternatively, in accorance with the terms contained
// in a written agreement between you and Syntext, Inc.
// 
// GNU GENERAL PUBLIC LICENSE USAGE
// Alternatively, this file may be used under the terms of the GNU General 
// Public License versions 2.0 or 3.0 as published by the Free Software 
// Foundation and appearing in the file LICENSE.GPL included in the packaging 
// of this file. In addition, as a special exception, Syntext, Inc. gives you
// certain additional rights, which are described in the Syntext, Inc. GPL 
// Exception for Syntext Serna Free Edition, included in the file 
// GPL_EXCEPTION.txt in this package.
// 
// You should have received a copy of appropriate licenses along with this 
// package. If not, see <http://www.syntext.com/legal/>. If you are unsure
// which license is appropriate for your use, please contact the sales 
// department at sales@syntext.com.
// 
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
// 
#include "structeditor/se_defs.h"
#include "editableview/EditableView.h"
#include "formatter/AreaPos.h"
#include <list>

class SelectionHistory {
public:
    typedef std::list<Selection>        SelectionList;
    typedef SelectionList::iterator     SelectionIterator;

    SelectionHistory() {
        lastDone_ = history_.end();
    }
    
    void    clear()
    {
        history_.erase(history_.begin(), history_.end());
        lastDone_ = history_.end();
    }

    void    add(const Selection& selection)
    {
        if (isRedoPossible()) {
            SelectionList::iterator redo_start = lastDone_;
            ++redo_start;
            history_.erase(redo_start, history_.end());
        }
        history_.push_back(selection);
        lastDone_ = --history_.end();
    }

    Selection undo()
    {
        if (isUndoPossible()) {
            if (lastDone_ != history_.begin())
                --lastDone_;
            else
                lastDone_ = history_.end();
        }
        if (lastDone_ != history_.end())
            return *lastDone_;
        return Selection(Formatter::TreeSelection(), 
                         GroveEditor::GroveSelection());
    }

    Selection redo()
    {
        if (isRedoPossible()) {
            if (history_.end() != lastDone_)
                ++lastDone_;
            else
                lastDone_ = history_.begin();
        }
        if (lastDone_ != history_.end())
            return *lastDone_;
        return Selection(Formatter::TreeSelection(), 
                         GroveEditor::GroveSelection());
    }

    bool isUndoPossible() const
    {
        return history_.end() != lastDone_;
    }

    bool isRedoPossible() const
    {
        return ((--history_.end()) != lastDone_) && history_.size();
    }

private:
    SelectionList       history_;
    SelectionIterator   lastDone_;
};

